Methods of operating roller bearing apparatuses including compliant rolling elements

ABSTRACT

In an embodiment, a roller bearing apparatus may include a rotor having first superhard raceway elements distributed circumferentially about an axis. Each first superhard raceway element includes a raceway surface positioned/configured to form a first portion of a raceway. The apparatus includes a stator including second superhard raceway elements generally opposed to the first superhard raceway elements. Each second superhard raceway element includes a raceway surface positioned/configured to form a second portion of the raceway. The apparatus includes rolling elements interposed between the rotor and stator and positioned and configured to roll on the raceway. One or more of the rolling elements may be configured to elastically deform on the raceway during use. At least a portion of the raceway exhibits a first modulus of elasticity greater than a second modulus of elasticity of at least a portion of the one or more of the rolling elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/713,096 filed on 13 Dec. 2012, the disclosure of which isincorporated herein, in its entirety, by this reference.

BACKGROUND

Roller bearing apparatuses are found in a variety of applications fromwind turbines to mining equipment. Typically, roller bearing apparatusesinclude two races, a plurality of rolling elements between the races,and a roller assembly that separates and guides the rolling elements.Usually one of the races is held fixed. As one of the races rotates, itcauses the rolling elements to rotate as well which, in turn, reducesrotational friction between the races. In addition to reducingrotational friction, roller bearing apparatuses typically supportbearing loads by transmitting loads between the rolling elements and theraces.

However useful, roller bearing apparatuses tend to wear out with useand/or fail without warning. For example, wind turbine gear boxescommonly suffer bearing failure at about one fifth of the designed lifeexpectancy. Many of these bearing failures result from micro pitting,race scuffing, galling, overheating, fatigue failure, flaking, fretting,and other damage due to friction and/or repeated loading and unloadingof the rolling elements on the races.

Therefore, manufacturers and users of roller bearing apparatusescontinue to seek improved roller bearing apparatus designs andmanufacturing techniques.

SUMMARY

Various embodiments of the invention relate to roller bearingapparatuses that include relatively compliant rolling elements. Thevarious embodiments of the bearing assemblies and apparatuses may beused in pumps, wind turbines, transmissions, subterranean drillingsystems, and other types of systems.

In an embodiment, a roller bearing apparatus may include a rotor havinga first plurality of superhard raceway elements distributedcircumferentially about an axis. Each of the first superhard racewayelements includes a raceway surface positioned and configured to from afirst portion of a raceway. The rotor also includes a first support ringthat carries the first superhard raceway elements. The roller bearingapparatus also includes a stator including a second plurality ofsuperhard raceway elements generally opposed the first superhard racewayelements. Each of the second superhard raceway elements includes araceway surface positioned and configured to form a second portion ofthe raceway. The stator also includes a second ring that carries thesecond superhard raceway elements. The roller bearing apparatus alsoincludes a plurality of rolling elements interposed between the rotorand the stator and positioned and configured to roll on the raceway. Oneor more of the rolling elements may be further configured to elasticallydeform on the raceway during use.

In an embodiment, at least a portion of the raceway exhibits a firstmodulus of elasticity greater than a second modulus of elasticity of atleast a portion of the one or more of the rolling elements. For example,the first modulus of elasticity may be about three (3) times greater toabout fifty (50) times greater than the second modulus of elasticity.

In an embodiment, one or more of the rolling elements may include one ormore superelastic materials that exhibit non-linear deformation duringuse. For example, the superelastic material may include a superelasticnickel-titanium alloy.

Further embodiments are directed to methods of manufacturing any of thedisclosed roller bearing apparatuses.

Other embodiments include applications utilizing the disclosed rollerbearing assemblies and apparatuses in various types of pumps,transmission, wind turbines, drilling systems and other applications.

Features from any of the disclosed embodiments may be used incombination with one another, without limitation. In addition, otherfeatures and advantages of the present disclosure will become apparentto those of ordinary skill in the art through consideration of thefollowing detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate several embodiments of the invention, whereinidentical reference numerals refer to identical or similar elements orfeatures in different views or embodiments shown in the drawings.

FIG. 1A is an isometric cutaway view of a radial roller bearingapparatus according to an embodiment;

FIG. 1B is an exploded isometric view of the radial roller bearingapparatus shown in FIG. 1A;

FIG. 1C is a cross-sectional view taken along line 1C-1C of the innerrace shown in FIG. 1A;

FIG. 1D is an isometric view of one of the superhard raceway elementsshown in FIG. 1C;

FIG. 1E is an isometric view of one of the roller elements shown in FIG.1B according to an embodiment;

FIG. 1F is a cross-sectional view taken along line 1F-1F of the rollerelement shown in FIG. 1E;

FIG. 1G is a cross-sectional view of a roller element according toanother embodiment;

FIG. 1H is a cross-sectional view of a roller element according toanother embodiment;

FIG. 1I is a partial side elevation view of the inner race and one ofthe rolling elements shown in FIG. 1A;

FIG. 1J is a partial cross-sectional view of the inner race and one ofthe rolling elements shown in FIG. 1A;

FIG. 2A is an exploded isometric view of a radial roller bearingaccording to according to another embodiment;

FIG. 2B is an exploded isometric view of a radial roller bearingaccording to another embodiment;

FIG. 3 is an isometric cutaway view of a radial roller bearing accordingto another embodiment;

FIG. 4 is an exploded view of a tapered roller bearing apparatusaccording to another embodiment;

FIG. 5 is an isometric cutaway view of an angular contact bearingaccording to another embodiment;

FIG. 6 is a partial isometric cutaway view of a rotary system accordingto an embodiment;

FIG. 7 is an isometric cutaway view of a thrust roller bearing apparatusaccording to an embodiment;

FIG. 8 is an exploded isometric view of a tapered thrust roller bearingapparatus according to another embodiment; and

FIG. 9 is a schematic isometric cutaway view of a subterranean drillingsystem that may utilize any of the disclosed roller bearing apparatusesaccording to various embodiments.

DETAILED DESCRIPTION

Embodiments of the invention relate to roller bearing apparatuses thatinclude rolling elements (e.g., superelastic, metallic, ornon-superabrasive rolling elements), motor assemblies that include suchroller bearing apparatuses, and related methods. FIG. 1A is an isometricview of a radial roller bearing apparatus 100 and FIG. 1B is an explodedisometric view of the radial roller bearing apparatus 100. The radialroller bearing apparatus 100 may be used in a wind turbine, a pump, atransmission, or other type of system.

As shown in FIGS. 1A and 1B, the radial roller bearing apparatus 100 mayinclude an inner race 102, an outer race 104, and a roller assembly 106.The inner race 102 (e.g., rotor or stator) may include a support ring108 and a plurality of superhard raceway elements 110. The support ring108 may define an opening 112 through which a shaft or spindle (notshown) of, for example, a wind turbine may extend. The outer race 104(e.g., rotor or stator) may extend about and receive the inner race 102and the roller assembly 106. The outer race 104 may include a supportring 120 and a plurality of superhard raceway elements 122. The rollerassembly 106 may be interposed between the inner race 102 and the outerrace 104 and may include a cage 126 and a plurality of rolling elements128. The superhard raceway elements 110, 122 of the inner race 102 andthe outer race 104, respectively, may be configured and positioned to atleast partially define a raceway for the rolling elements 128. A racewayis a substantially continuous or discontinuous surface or surfaces overwhich the rolling elements 128 roll over/run on. Rotation of the innerrace 102 and/or the outer race 104 may cause the rolling elements 128 toroll or run on the raceway formed between the superhard raceway elements110 and the superhard raceway elements 122. As described in more detailbelow, the rolling elements 128 and/or the superhard raceway elements110, 122 may include one or more features, either alone or incombination, configured to help reduce wear and/or failure of (e.g.,flaking, strain, pitting, or combinations thereof) of the radial rollerbearing apparatus 100. For example, in an embodiment, the rollingelements 128 may include one or more metallic materials (e.g., steel ora superelastic alloy) and/or non-superabrasive materials and the racewaymay include one or more superhard or superabrasive materials such aspolycrystalline diamond, polycrystalline cubic boron nitride, siliconcarbide, tungsten carbide, or any combination of the foregoing superhardmaterials. By varying the material design between the rolling elements128 and/or the raceway, common failure modes such as welding, galling,and/or scuffing may be reduced.

The inner race 102 may form a rotor or a stator of the radial rollerbearing apparatus 100. In the illustrated embodiment, the support ring108 is substantially cylindrical and defines the opening 112. Thesupport ring 108 may be circular and made from a variety of differentmaterials. For example, the support ring 108 may comprise carbon steel,stainless steel, alloy steel, tungsten carbide, or another suitablematerial. In the illustrated embodiment, the support ring 108 exhibitsan inner surface that is substantially congruent with respect to anouter surface. The support ring 108 may also include a plurality ofrecesses 116 (FIG. 1C) formed therein.

The inner race 102 may also include the plurality of superhard racewayelements 110 each of which includes a substrate 136 and a superhardtable 134 bonded to the substrate 136. The superhard raceway elements110 are illustrated being distributed circumferentially about a rotationaxis 114. Each of the superhard raceway elements 110 may include aconvexly-curved raceway surface 118 that defines at least part of theraceway. In the illustrated embodiment, gaps 132 or other offsets may belocated between adjacent ones of the superhard raceway elements 110. Awidth of one or more of the gaps 132 or an average width of the gaps 132may be about 0.00020 inches to about 0.100 inches, and more particularlyabout 0.00020 inches (0.00508 mm) to about 0.020 inches (0.508 mm). Inother embodiments, one or more of the gaps 132 may exhibit larger orsmaller widths. Optionally, the gaps 132 may be configured to limitlubricating fluid from being able to leak between adjacent superhardraceway elements 110. For example, the gaps 132 may exhibit a relativelysmall width. As the gaps 132 decrease in size, it may become moredifficult for lubricating fluid to flow between the superhard racewayelements 110. However, it should be noted that in at least someoperational conditions, entrained lubricating fluid in the gaps 132 mayassist with formation of a hydrodynamic film on at least one of theraceway surfaces 118. In other embodiments, the gaps 132 may exhibit arelatively large width. As the width of the gaps 132 increases, the gaps132 may be configured to improve heat transfer. For example, the gaps132 may be configured to form flow paths for the lubricating fluid toflow over and/or around the superhard raceway elements 110. As the sizeof the gaps 132 increase, fluid flow and heat transfer may more fullydevelop between adjacent superhard raceway elements 110. Thus, byvarying the configuration and size of the gaps 132, the gaps 132 may beoptionally configured to impart a desired amount of heat transfer and/orhydrodynamic film formation during operation.

In an embodiment, the gaps 132 may be at least partially occupied by aportion of the support ring 108. Such a configuration may increase thecontact surface between the support ring 108 and each of the superhardraceway elements 110 to help affix the superhard raceway elements 110 tothe support ring 108. In other embodiments, the recesses 116 may beconfigured and positioned such that the gaps 132 are omitted. Forexample, the recesses 116 may be interconnected to form a slot orchannel such that adjacent superhard raceway elements 110 are adjacentto one another and/or about one another.

Referring now to FIG. 1C, each of the superhard raceway elements 110 maybe partially disposed in a corresponding one of the recesses 116 of thesupport ring 108 and secured partially therein via brazing,press-fitting, threadly attaching, fastening with a fastener,combinations of the foregoing, or another suitable technique. As usedherein, a “superhard raceway element” is a raceway element including araceway surface that is made from a material exhibiting a hardness thatis at least as hard as tungsten carbide.

In any of the embodiments disclosed herein, the superhard racewayelements (e.g., superhard raceway elements 110) may be made from anumber of different superhard materials, such as polycrystallinediamond, polycrystalline cubic boron nitride, silicon carbide, tungstencarbide, or any combination of the foregoing superhard materials. Forexample, superhard raceway elements having a PCD table may be formed andbonded to a substrate using an ultra-high pressure, ultra-hightemperature (“HPHT”) sintering process. Such superhard raceway elementshaving a PCD table may be fabricated by placing a cemented carbidesubstrate, such as a cobalt-cemented tungsten carbide substrate, into acontainer or cartridge with a volume of diamond particles positioned ona surface of the cemented carbide substrate. A number of such cartridgesmay be loaded into an HPHT press. The substrates and diamond particlesmay then be processed under HPHT conditions in the presence of acatalyst material that causes the diamond particles to bond to oneanother to form a diamond table having a matrix of bonded diamondcrystals. The catalyst material is often a metal-solvent catalyst, suchas cobalt, nickel, or iron, which facilitates intergrowth and bonding ofthe diamond particles. In an embodiment, a constituent of the cementedcarbide substrate, such as cobalt from a cobalt-cemented tungstencarbide substrate, liquefies and sweeps from a region adjacent to thevolume of diamond particles into interstitial regions between thediamond particles during the HPHT process. The cobalt may act as acatalyst to facilitate the formation of bonded diamond grains.

In any of the embodiments disclosed herein, the polycrystalline diamondtable may be leached to at least partially or substantially completelyremove the metal-solvent catalyst (e.g., cobalt, iron, nickel, or alloysthereof) that was used to initially sinter precursor diamond particlesthat form the polycrystalline diamond. In another embodiment, aninfiltrant used to re-infiltrate a preformed leached polycrystallinediamond table may be leached or otherwise removed to a selected depthfrom a raceway surface. Moreover, in any of the embodiments disclosedherein, the polycrystalline diamond may be unleached and include ametal-solvent catalyst (e.g., cobalt, iron, nickel, or alloys thereof)that was used to initially sinter the precursor diamond particles thatform the polycrystalline diamond or an infiltrant used to re-infiltratea preformed leached polycrystalline diamond table. Other examples ofmethods for fabricating the superhard raceway elements are disclosed inU.S. Pat. Nos. 7,866,418, 7,842,111; and 8,236,074, the disclosure ofeach of which is incorporated herein, in its entirety, by thisreference.

The diamond particles that may form the polycrystalline diamond in thesuperhard table 134 may also exhibit a larger size and at least onerelatively smaller size. As used herein, the phrases “relatively larger”and “relatively smaller” refer to particle sizes (by any suitablemethod) that differ by at least a factor of two (e.g., 30 μm and 15 μm).According to various embodiments, the diamond particles may include aportion exhibiting a relatively larger size (e.g., 40 μm, 30 μm, 20 μm,15 μm, 12 μm, 10 μm, 8 μm) and another portion exhibiting at least onerelatively smaller size (e.g., 6 μm, 5 μm, 4 μm, 3 μm, 2 μm, 1 μm, 0.5μm, less than 0.5 μm, 0.1 μm, less than 0.1 μm). In an embodiment, thediamond particles may include a portion exhibiting a relatively largersize between about 10 μm and about 40 μm and another portion exhibitinga relatively smaller size between about 1 μm and about 4 μm. In someembodiments, the diamond particles may comprise three or more differentsizes (e.g., one relatively larger size and two or more relativelysmaller sizes), without limitation. Upon HPHT sintering the diamondparticles to form the polycrystalline diamond, the polycrystallinediamond may, in some cases, exhibit an average grain size that is thesame or similar to any of the diamond particles sizes and distributionsdiscussed above. Additionally, in any of the embodiments disclosedherein, the superhard raceway elements 110 may be free-standing (e.g.,substrateless) and formed from a polycrystalline diamond body that is atleast partially or fully leached to remove a metal-solvent catalystinitially used to sinter the polycrystalline diamond body. In anembodiment, the leached polycrystalline diamond body may be formed toexhibit a porosity of about 1-10% by volume such that the pores of thepolycrystalline diamond body may be impregnated with lubricant to assistin minimizing friction caused by contact of the rolling elements 128 onthe raceway. In other embodiments, the polycrystalline diamond body mayexhibit a selected porosity that is higher or lower.

At least some of the superhard raceway elements 110 may comprise asuperhard table 134 including a convexly-curved raceway surface 118(i.e., curving to lie on an imaginary cylindrical surface) as shown inFIGS. 1B and 1C. Each of the superhard tables 134 may be bonded to acorresponding substrate 136. Optionally, one or more of the superhardraceway elements 110 may exhibit a peripherally-extending edge chamferand/or radius. However, in other embodiments, the edge chamfer or radiusmay be omitted.

The superhard raceway elements 110 may have any suitable individualshape. As best shown in FIG. 1D, each superhard raceway element 110 mayhave a generally rounded rectangular-shaped body including a pair ofgenerally parallel side surfaces 110A, a first end surface 110B, and asecond end surface 110C. The side surfaces 110A may extend between thefirst end surface 110B and the second end surface 110C and vice versa.In the illustrated embodiment, both the first end surface 110B and thesecond end surface 110C may have a generally convex curvature. In otherembodiments, the superhard raceway elements 110 may have a generallyelliptical shape, a generally wedge-like shape, a generally cylindricalshape, or any other suitable body shape.

In an embodiment, the superhard raceway elements 110 may be configuredto help prevent the rolling elements 128 from lodging in the gaps 132and/or to maintain contact with the superhard raceway elements 110 asthe rolling elements 128 roll over the raceway surfaces 118 during use.For example, at least one or both of side surfaces 110A of the superhardraceway elements 110 may be oriented at an oblique angle θ (shown inFIG. 1I) relative to the rotation axis 114. In some embodiments, each ofthe superhard raceway elements 110 may be substantially at the samegeneral oblique angle θ relative to the rotation axis 114, while inother embodiments, the oblique angles θ may be different. In anembodiment, the angle θ may be about 40 degrees to about 85 degrees;about 50 degrees to about 80 degrees; or about 55 degrees to about 75degrees. In other embodiments, the angle θ may be larger or smaller. Theangle θ may be selected such that only a portion of one of the rollingelements 128 extends across one of the gaps 132 between two of thesuperhard raceway elements 110 at any given time, while the rollingelement 128 maintains contact with the two superhard raceway elements110. Put another way, the line of contact of the rolling element 110 andthe superhard raceway elements 110 may be misaligned related to theextension of the gap in length. Thus, the rolling elements may avoidbecoming impeded by the gaps 132 during operation. Such a configurationmay provide a smoother ride on the raceway for the rolling elements 128.

Referring again to FIGS. 1A and 1B, the outer race 104 may exhibit aconfiguration similar to the inner race 102. For example, the outer race104 may include the support ring 120 and the superhard raceway elements122 mounted or otherwise attached to the support ring 120 with recesses117 formed in an inner surface of the support ring 120. In theillustrated embodiment, the support ring 120 may include an outersurface substantially parallel to the inner surface. The recesses 117may be configured to generally correspond to the recesses 116 formed inthe support ring 108 of the inner race 102. The superhard racewayelements 122 may exhibit any selected geometric shape. In someembodiments, the superhard raceway elements 122 may have a generallyrounded rectangular shape, a cylindrical shape, a wedge-like shape, orany other suitable geometric shape. Each of the superhard racewayelements 122 may include a concavely-curved raceway surface 124. Thesuperhard raceway elements 122 may be made from any of the materialsdiscussed above for the superhard raceway elements 110 and configuredand positioned to form at least a portion of the raceway for the rollingelements 128 to roll/run on. For example, at least some of the superhardraceway elements 122 may comprise superhard table 134 bonded to acorresponding substrate 136.

In an embodiment, rotation of the inner race 102 and/or the outer race104 may cause the rolling elements 128 to roll/run on the raceway formedbetween the raceway surface 118 of the superhard raceway elements 110and the raceway surfaces 124 of the superhard raceway elements 122. Byforming the raceway with the superhard raceway elements 110, 122,deformation of the support rings 108, 120 and or the risk of fatigue maybe reduced because the rolling elements 128 generally avoid contact withthe support rings 108, 120. Moreover, fatigue at the contact surfacebetween the superhard raceway elements 110, 122 and the rolling elements128 may be reduced because superhard material does not deform as much asa traditional raceway surface (i.e., steel) due to the superhard racewaymaterial's high modulus of elasticity. For example, in an embodiment,the superhard table 134 may exhibit a modulus of elasticity betweenabout 800 GPa and about 1200 GPa (e.g., about 800 GPa to about 850 GPa,or about 841 GPa). In other embodiments, the superhard table 134 mayexhibit a selected modulus of elasticity that is higher or lower. In anembodiment, the superhard raceway elements 110, 122 may enhance thegeneral load capacity of the radial roller bearing apparatus 100.Further, the superhard raceway elements 110, 122 may form a raceway thatexhibits lower friction and is more resistant to abrasion and corrosionthan a traditional raceway (i.e., steel). This may be particularlyadvantageous for wind turbine gearbox applications where frequent startsand stops are expected. Optionally, a relatively high thermalconductivity of the superhard raceway elements 110, 122 may also helpreduce adhesive wear and resulting scuffing and micropitting of theraceway and/or the rolling elements 128. For example, the raceway (i.e.,raceway surfaces 118, 124) may exhibit a thermal conductivity of about543 W/m-K which is about twelve (12) times the thermal conductivity ofsteel. In other embodiments, the raceway may exhibit a thermalconductivity of at least about 300 W/m-K; at least about 800 W/m-K; atleast about 1300 W/m-K; or about 2000 W/m-K. In addition, the racewaymay exhibit a thermal conductivity of about 300 W/m-K to about 2000W/m-K; about 700 W/m-K to about 1600 W/m-K; or about 1000 W/m-K to about1300 W/m-K. In other embodiments, the thermal conductivity of theraceway may be larger or smaller. Accordingly, heat generated byeventual skidding and/or slipping of the rolling elements 128 on theraceway may be quickly conducted away from the raceway to reduceadhesive wear and resulting scuffing and/or micro-pitting. Because ofthe raceway's large thermal conductivity, heat generated by eventualskidding and slipping of the rolling elements 128 may be more quicklyconducted away from the contact surface between the rolling elements 128and the raceway. In other embodiments, the raceway surfaces 118, 124and/or the raceway may exhibit thermal conductivities that are higher orlower.

As discussed above, the roller assembly 106 may include the cage 126 andthe rolling elements 128. The cage 126 may include a plurality of cagepockets 130 formed in the cage 126 and distributed circumferentiallyabout the rotation axis 114. Each of the cage pockets 130 may beconfigured to retain one of the rolling elements 128. In the illustratedembodiments, each of the cage pockets 130 may exhibit a substantiallyrectangular cross-sectional shape. In other embodiments, one or more ofthe cage pockets 130 may exhibit a generally elliptical cross-sectionalshape, a generally circular cross-sectional shape, a generally squarecross-sectional shape, a generally trapezoidal cross-sectional shape, orany other suitable cross-sectional shape. The cage pockets 130 may bearranged in a single row about the rotation axis 114. In otherembodiments, the cage pockets 130 may be arranged in two rows, threerows, four rows, or any other number of rows. The cage 126 may be madefrom any number of suitable materials. For example, the cage 126 maycomprise a metal, an alloy, an alloy steel, carbon steel, stainlesssteel, brass, tungsten carbide, or any other suitable material. Therolling elements 128 may be rotatably mounted within the cage pockets130, with each of the rolling elements 128 having a longitudinalrotation axis substantially parallel to the rotation axis 114.

FIGS. 1E and 1F are isometric and cross-sectional views, respectively,of one of the rolling elements 128 removed from the cage 126. Therolling element 128 may exhibit a generally cylindrical body having adiameter D as well as an upper surface 128A and a lower surface 128Bdefining a length L extending therebetween. In an embodiment, the uppersurface 128A and the lower surface 128B may be generally planar. Inother embodiments, the upper surface 128A and/or the lower surface 128Bmay be generally curved, generally conical, combinations thereof, or mayhave any other suitable configuration. Variations in the length L and/orthe diameter D of the one or more rolling elements 128 may be configuredto help resist fatigue and/or ultimate failure and/or influence therotational speed of the rolling elements 128. In addition, therelationship between the length L of one or more of the rolling elements128 and the diameter D of the one or more rolling elements 128 may beconfigured to provide a selected contact area with the raceway use, helpresist fatigue, damage, and/or ultimate failure. For example, thediameter D of at least one of the rolling elements 128 may be at least:about ten percent (10%); about twenty percent (20%); about thirtypercent (30%); about forty percent (40%); about fifty percent (50%);about sixty percent (60%); about seventy percent (70%); about eightypercent (80%); about ninety percent (90%); about one hundred percent(100%); or about one hundred and ten percent (110%) of the length L ofat least one of the rolling elements 128. In addition, the diameter D ofat least one of the rolling elements 128 may be about ten percent (10%)to about two hundred percent (200%); or about one hundred percent (100%)of the length L of at least one of the rolling elements 128. In otherconfigurations, the rolling elements 128 may exhibit a generallyspherical body, a generally conical body, a generally hourglass-likebody, or any other suitable geometric shape.

In an embodiment, the rolling elements 128 (or any of the rollingelements disclosed herein) may at least partially comprise one or moresuperelastic materials. For example, typical superelastic materialsexhibit non-linear elastic deformation during use. Non-linear elasticdeformation is elastic deformation characterized by a non-linearrelationship between stress and strain. Examples of suitablesuperelastic materials include, but are not limited to, nickel-titaniumalloys (e.g., nitinol or SM-100™ which is a more wear resistantnitinol-type alloy), copper-aluminum-nickel alloys, copper-tin alloys,copper-zinc alloys, iron-manganese-silicon alloys, combinations thereof,or any other suitable superelastic material. Consequently, the rollingelements 128 may exhibit a larger elastic resilience than rollingelements formed of other materials (i.e. steel) such that the rollingelements 128 may help enhance fatigue life of the radial roller bearingapparatus 100. In the illustrated embodiment, the rolling element 128may be substantially formed of a single superelastic material as shownin FIG. 1F. As shown in FIG. 1G, in other embodiments, the rollingelement 128 may include at least an inner core 129A surrounded by anouter layer and/or coating 129B made from any of the superelasticmaterial disclosed herein. The inner core 129A may comprise carbonsteel, stainless steel, alloy steel, tungsten carbide, or anothersuitable material. In other embodiments, the rolling element 128 mayinclude two, three, four, or any suitable number of layers, portions, orcoatings of superelastic materials. In other embodiments, the rollingelement 128 may include a portion including one or more superelasticmaterials and another portion not including superelastic materials. Inyet other embodiments, the rolling element 128 may not includesuperelastic materials and/or may include one or more metallic and/ornon-superabrasive materials. In other embodiments, as shown in FIG. 1H,one or more of the rolling elements 128 may comprise an outer shell 129Bat least partially defining a hollow interior space extending at leastpartially through the rolling element 128. For example, in anembodiment, one or more of the rolling elements 128 may comprise agenerally cylindrical PCD body with the inner core removed to form theouter shell 129B. The outer shell 129B may comprise a superelasticmaterial, PCD, or another suitable material. Such a configuration mayhelp provide flexibility and/or abrasion resistance to the rollingelement 128. In other embodiments, such a configuration may help lowerthe inertia of the rolling element 128.

FIG. 1J is a partial cross-sectional view of one of the rolling elements128 running on a portion of the raceway formed by the superhard racewayelements 122 of the outer race 104. As shown, the raceway and/or therolling elements 128 may also be configured such that the portion of oneor more of the rolling elements 128 in contact with the racewayelastically deforms to provide a selected contact area during use.Elastic deformation is a change in shape of a material at a stress thatis recoverable after the stress is removed. For example, one or more ofthe rolling elements 128 may exhibit a modulus of elasticity of about 20GPa to about 109 GPa. As another example, common superelasticnickel-titanium alloys (e.g., nitinol) from which one or more of therolling elements 128 may be made have an elastic modulus of about 70 GPato about 85 GPa in the austenite phase and an elastic modulus of about28 GPa to about 41 GPa in the stress-induced martensite phase. Thus, insome embodiments, the nickel-titanium alloy may exhibit a martensitedeformation temperature (“M_(d)”) that is sufficiently high so thatstress-induced martensite is generated during loading and operation ofthe roller bearing apparatus 100 in order to rely on the relatively lowelastic modulus of the stress-induced martensite phase. For example,M_(d) of the superelastic nickel-titanium alloys used herein may beabout 100° C. to about 300° C., such as 150° C. to about 200° C. orabout 100° C. to about 145° C. In other embodiments, one or more of therolling elements 128 may exhibit a modulus of elasticity of about 60 GPato about 90 GPa.

Various embodiments also contemplate that the raceway may exhibit amodulus of elasticity that exceeds a modulus of elasticity of one ormore of the rolling elements. For example, the modulus of elasticity ofthe raceway may be at least: about forty (40) times greater, aboutthirty (30) times greater, about twenty (20) times greater, aboutfifteen (15) times greater; about twelve (12) times greater; about nine(9) times greater; about six (6) times greater; or about three (3) timesgreater than a modulus of elasticity of one or more of the rollingelements 128. In addition, the modulus of elasticity of raceway may beat least: about three (3) times greater to about fifty (50) timesgreater; about five (5) times greater to about fifty (50) times greater,about thirty (30) times greater to about forty five (45) times greater,about twenty (20) times greater to about forty five (45) times greater,about seven (7) times greater to about sixteen (16) times greater; orabout four (4) times greater to about fourteen (14) times greater thanthe modulus of elasticity of one or more of the rolling elements 128.The difference between the modulus of elasticity of the rolling elements128 and the raceway may enhance resistance of the radial roller bearingapparatus 100 to shock and/or vibration loading. In otherconfigurations, the modulus of elasticity of one or more of the rollingelements 128 and the modulus of elasticity of the raceway may be largeror smaller relative to each other. Such a configuration may enhanceresistance of the radial roller bearing apparatus 100 to shock andvibration loading. Moreover, in other embodiments, the roller elements128 and the superhard raceway elements 110, 122 may include differentmaterials such that common failure modes such as welding, galling,and/or scuffing may be reduced. Thus, by varying the material design ofthe rolling elements 128 and/or the superhard raceway elements 110, 122,the rolling elements 128 and/or the superhard raceway elements 110, 122may be configured to enhance the bearing life of the radial rollerbearing apparatus 100 in one or more different ways.

In an embodiment, the roller elements 128 and the raceway may beconfigured to influence elastohydrodynamic lubrication and/orelastohydrodynamic fluid film formation. For example, where the loadingconditions, modulus of elasticity of the raceway, modulus of elasticityof the rolling elements 128, the rotational speed of the rotor, orcombinations thereof is sufficient, an elastohydrodynamic fluid film maydevelop between the raceway and the rolling elements 128. The portion ofthe rolling elements 128 in contact with the raceway (i.e., racewaysurfaces 118 and/or 124) may elastically deform such that the rollingelements 128 exhibit a greater contact area with the raceway to generateor facilitate fluid formation between the rolling elements 128 andadjacent superhard raceway elements 110 and/or superhard racewayelements 122. In an embodiment, the difference between the modulus ofelasticity of the rolling elements 128 and the raceway may help changethe geometry and/or nature of contact between the rolling elements 128and the raceway. For example, a larger deformation of the rollingelements 128 may help form a broader area of contact between the rollingelements 128 and the raceway and also a broader area in whichelastohydrodynamic lubrication and/or elastohydrodynamic fluid filmformation may occur. Such a configuration may help promote effectiveelastohydrodynamic lubrication and/or elastohydrodynamic fluid filmformation at lower speeds. Consequently, the rolling elements 128 may beconfigured to help form a fluid film having sufficient pressure and atappropriate loading conditions, and/or to prevent or limit physicalcontact between the respective raceway and the rolling elements 128 tothereby reduce wear of the superhard raceway elements 110, 122 and/orthe rolling elements 128. In such a situation, the radial roller bearingapparatus 100 may be described as operating hydrodynamically. When therotational speed of the rotor is reduced, the pressure of the fluid filmmay not be sufficient to prevent the rolling elements 128 and theraceway from contacting each other. Thus, by selecting the modulus ofelasticity of the rolling elements 128 and the raceway, the radialroller bearing apparatus 100 may be configured to exhibit a desiredamount of elastohydrodynamic lubrication and/or fluid film formationduring certain operating conditions.

In other embodiments, the radial roller bearing apparatus may include acageless roller assembly. For example, FIG. 2A is an exploded isometricview of an embodiment of a radial roller bearing apparatus 200A. Theprinciples of the radial roller bearing apparatus 200A may be employedwith any of the embodiments described with relation to FIGS. 1A through1J and vice versa. In the radial roller bearing apparatus 200A, aplurality of elongated rolling elements 228A are circumferentiallydistributed about a rotation axis 214A and interposed between an innerrace 202A having superhard raceway elements 210A and an outer race 204Ahaving superhard raceway elements 222A. As shown, a roller assembly 206Amay include the rolling elements 228A positioned between the inner race202A and the outer race 204A without a cage to separate the rollingelements 228A. Thus, each of the rolling elements 228A may push againstother rolling elements 228A to hold the rolling elements 228A in place.The rolling elements 228A may be positioned configured such that therolling elements may rotate therebetween, with each of the elongatedrolling elements 228A having a longitudinal axis substantially parallelto the rotation axis 214A. Optionally, the inner race 202A and/or theouter race 204A may include flange features 242A configured to helpmaintain the position of rolling elements 228A between the inner race202A and the outer race 204A. Moreover, the rolling elements 228A may bemade from any of the materials discussed above for the rolling elements128.

FIG. 2B is an exploded isometric view of another embodiment of acageless radial roller bearing apparatus 200B. The principles of theradial roller bearing apparatus 200A may be employed with any of theembodiments described with relation to FIGS. 1A through 2A and viceversa. In the radial roller bearing apparatus 200B, a plurality ofgenerally spherical rolling elements 228B are circumferentiallydistributed about a rotation axis 214B and interposed between an innerrace 202B having superhard raceway elements 210B and an outer race 204Bhaving superhard raceway elements 222B. Like radial roller bearingapparatus 200A, a roller assembly 206B may include the rolling elements228B positioned between the inner race 202B and the outer race 204Bwithout a cage to separate the spherical rolling elements 228B. Thus,each of the rolling elements 228B may help hold one another in place.Optionally, the inner race 202B and/or the outer race 204B may includeflange features 242B configured to help maintain the position of therolling elements 228B between the inner race 202B and the outer race204B. Moreover, the rolling elements 228B may be made from any of thematerials discussed above for the rolling elements 128.

In yet other embodiments, the radial roller bearing apparatus mayinclude a plurality of rows of rolling elements and/or superhard racewayelements. For example. FIG. 3 is an isometric cutaway view of a radialroller bearing apparatus 300. The radial roller bearing apparatus 300has many of the same components and features that are included in theradial roller bearing apparatuses 100 and 200 of FIGS. 1A-2B. Therefore,in the interest of brevity, the components and features of the radialroller bearing apparatuses 100 and 300 that correspond to each otherhave been provided with identical reference numerals, and an explanationthereof will not be repeated. However, it should be noted that theprinciples of the radial roller bearing apparatus 300 may be employedwith any of the embodiments described with respect to FIGS. 1A through2B.

In the radial roller bearing apparatus 300, a roller assembly 306 may beinterposed between an inner race 302 and an outer race 304 and mayinclude a cage 326 and a plurality of rolling elements 328. The cage 326of the roller assembly 306 may include a plurality of cage pockets 330formed in the cage 326 and distributed circumferentially about arotation axis (not shown) in two rows. Each of the cage pockets 330 maybe configured to retain one of the rolling elements 328. Similar to thecage pockets 130, each of the cage pockets 330 may exhibit asubstantially rectangular cross-sectional shape. In other embodiments,one or more of the cage pockets 330 may exhibit a generally ellipticalcross-sectional shape, a generally circular cross-sectional shape, agenerally square cross-sectional shape, a generally trapezoidalcross-sectional shape, or any other suitable cross-sectional shape. Therolling elements 328 may be rotatably mounted within the cage pockets330, with each of the rolling elements 328 having a longitudinalrotation axis substantially parallel to the rotation axis 314. Similarto the superhard raceway elements 110, 120, the inner race 302 mayinclude superhard raceway elements 310 and the outer race 304 mayinclude superhard raceway elements 322, both configured and positionedto at least partially define a raceway for the rolling elements 328. Inthe illustrated embodiment, the superhard raceway elements 310 and/or322 may be sized and distributed about the rotation axis 314 to at leastpartially define two raceways, one for each row of rolling elements 328.In other embodiments, the superhard raceway elements 310 and/or 322 maybe sized and distributed about the rotation axis 314 to at leastpartially define a single raceway for both of the two rows of rollingelements 328. Optionally, as illustrated, the inner race 302 and/or theouter race 304 may include flange features 342 configured to helpmaintain the rolling elements 328 between the inner race 302 and theouter race 304.

Superhard raceway elements 310 and/or 322 may include any of thematerials discussed above for the superhard raceway elements 110. Forexample, at some of the superhard raceway elements 310 and/or 322 mayinclude a superhard material such as a PCD. Moreover, the rollingelements 328 may be made from any of the materials discussed above forthe rolling elements 128. For example, one or more of the rollingelements 328 may include one or more superelastic materials (e.g.,nickel-titanium alloys). In addition, the cage 326 may be made from anyof the materials discussed above for the cage 126. For example, cage 326may comprise a metal, an alloy, an alloy steel, carbon steel, stainlesssteel, brass, tungsten carbide, or any other suitable material.

In an embodiment, the material design of the superhard raceway elements310, 322 and/or the rolling elements 328 may be configured to influencethe operational life and/or performance of the radial roller bearingapparatus 300. For example, by forming the raceway with the superhardraceway elements 310, 322 including one or more superhard materials,fatigue at the contact surface between the superhard raceway elements310, 322 and the rolling elements 328 may be reduced because superhardmaterial will not deform as much as a traditional raceway surface (i.e.,steel) due to the superhard raceway material's high modulus ofelasticity. In other embodiments, the superhard bearing elements 310and/or 322 or raceway may be configured to exhibit a modulus ofelasticity that exceeds a modulus of elasticity of one or more of therolling elements 328 such that resistance of the radial roller bearingapparatus 300 to shock, vibration loading, and/or common failure modessuch as welding, galling, and/or scuffing may be enhanced.

While the roller assembly 306 is illustrated including two rows of cagepockets 330 and/or rolling elements 328, the roller assembly 306 mayinclude three, four, five, or any other suitable number of rows of cagepockets 330 and/or rolling elements 328. Moreover, while each of therows of cage pockets 330 and/or rolling elements 328 are illustratedexhibiting similar configurations, in other embodiments, theconfiguration of each row may vary. For example, the roller assembly 306may include a first row of cage pockets 330 and/or rolling elements 328that are physically larger (e.g., radius and/or length) than a secondrow of cage pockets 330 and/or rolling elements 328. In addition, whiletwo rows are superhard raceway elements 310 and 322 are illustrated, inother embodiments, the inner race 302 and/or the outer race 304 mayinclude one row, three rows, four rows, or any suitable number of rowsof superhard raceway elements.

Embodiments of the invention contemplate that the concepts used in theradial roller bearing apparatuses described above may also be employedin a variety of different bearings including, but not limited to, thrustroller bearings, spherical roller bearings, tapered roller bearings,angular contact bearings, ball bearings, linear motion bearings,combinations thereof, or any other suitable type of bearing. Forexample, FIG. 4 is an exploded isometric view of a tapered rollerbearing apparatus 400 according to an embodiment. It should be notedthat the principles of the tapered roller bearing apparatus 400 may beemployed with any of the embodiments described with respect to FIGS. 1Athrough 3 and vice versa.

The tapered roller bearing apparatus 400 may include an inner race 402,an outer race 404, and a roller assembly 406. The inner race 402 mayinclude a support ring 408 and a plurality of superhard raceway elements410. The outer race 404 may include a support ring 418 and a pluralityof superhard raceway elements 422. In an embodiment, the support ring408 may be configured as a cone and the support ring 418 may beconfigured as a cup. For example, the support ring 418 may extend aboutand receive the support ring 408. The inner surface 408A of the supportring 408 may be substantially incongruent relative to the outer surface408B (into which the superhard raceway elements 410 are positioned) ofthe support ring 408 and substantially congruent relative to the outersurface 418B of the support ring 418. The outer surface 418B of supportring 418 may be curved to lie substantially on an imaginary cylindricalsurface. Further, the inner surface 418A (into which the superhardraceway elements 422 are positioned) of the support ring 418 may besubstantially incongruent relative to the outer surface 418B of thesupport ring 418 and substantially congruent relative to the curvedouter surface 408B of the support ring 408.

As shown, the roller assembly 406 may be interposed between the innerrace 402 and the outer race 404. The roller assembly 406 may include acage 426 and a plurality of generally cylindrical rolling elements 428.In an embodiment, the support ring 408 and/or the support ring 418 mayinclude respective flange features (not shown) configured to helpmaintain the rolling elements 428 between the inner race 402 and theouter race 404. In other embodiments, the flange features may be omittedfrom both the support ring 408 and the support ring 418.

In an embodiment, the superhard raceway elements 410 of the inner race402 and the superhard raceway elements 422 of the outer race 404 may bepositioned and configured to at least partially define a raceway for therolling elements 428 to run over or roll on during use. For example, thesuperhard raceway elements 410 may be positioned and configured to forma portion of the raceway on the outer surface 408B of the support ring408 curved to lie substantially on an imaginary conical surface.Similarly, the superhard raceway elements 422 may be positioned andconfigured on the inner surface 418A of the support ring 418 to formanother portion of the raceway curved to lie substantially on animaginary conical surface.

In an embodiment, the cage 426, including the rolling elements 428, mayform at least a portion of a cone (e.g., a frustoconical ring) and maybe configured to be interposed between the conical inner surface 418A ofthe support ring 418 and the conical outer surface 408B of the supportring 408. When the tapered roller bearing apparatus 400 is loaded withan external force (e.g., wind load), the conical geometric relationshipof inner surface 418A and the outer surface 408B may transform theexternal force into separate load components. Such a configuration mayallow the thrust roller bearing apparatus 400 to support both radial andaxial loads. In addition, the conical geometric relationship and/orcurvature of the raceway may help allow for some degree of shaftmisalignment and/or deflection during operation.

While the raceway is shown including one or more portions curved to liesubstantially on an imaginary conical surface, one or more portions ofthe raceway may be curved to lie substantially on an imaginary sphericalsurface or another curved surface. Moreover, while generally cylindricalrolling elements 428 are illustrated, in other embodiments, the cage 426may include one or more tapered rolling elements 428, one or moregenerally spherical rolling elements 428 (e.g., a crowned (barrel) typeshape), and/or one or more rolling elements 428 having other suitablegeometric shapes.

Superhard raceway elements 410 and/or 422 may include any of thematerials discussed above for the superhard raceway elements 110. Forexample, at least some of the superhard raceway elements 410 and/or 422may include a PCD table. In addition, the rolling elements 428 may bemade from any of the materials discussed above for the rolling elements128. For example, one or more of the rolling elements 428 may includeone or more superelastic materials (e.g., nickel titanium alloys) and/orsteel. The cage 426 may also be made from any of the materials discussedabove for the cage 126. For example, cage 426 may comprise a metal, analloy, an alloy steel, carbon steel, stainless steel, brass, tungstencarbide, or any other suitable material. In an embodiment, the materialdesign of the superhard raceways elements 410, 422 and/or the rollingelements 428 may be configured to influence the operational life and/orperformance of the tapered roller bearing apparatus 400. For example, byforming the raceway with the superhard raceway elements 410, 422including one or more selected superhard materials, fatigue at thecontact surface between the superhard raceway elements 410, 422 and therolling elements 428 may be reduced because superhard material will notdeform as much as a traditional raceway surface (i.e., steel). This isin part due to the superhard raceway material's high modulus ofelasticity.

FIG. 5 is a partial cutaway view of an angular contact ball bearingapparatus 900 according to an embodiment. It should be noted that theprinciples of the angular contact ball bearing apparatus 900 may beemployed with any of the embodiments described with respect to FIGS. 1Athrough 4 and vice versa. The angular contact ball bearing apparatus 900may include an inner race 902, an outer race 904, and a roller assembly906. The inner race 902 may include a support ring 908 having an innershoulder 908A and an upper shoulder 908B and a plurality of superhardraceway elements 910. The outer race 904 may include a support ring 918having an outer shoulder 918C and a lower shoulder 918D and a pluralityof superhard raceway elements 922. The support ring 918 of the outerrace 904 may extend about and receive the support ring 908 of the innerrace 902.

In an embodiment, superhard raceway elements 922 may be positionedbetween outer shoulder 918C and lower shoulder 918D on an inner surfaceof support ring 918. Each of the superhard raceway elements 922 may bepartially disposed in a corresponding recess formed in the inner surfaceof support ring 918 and secured partially therein via brazing,press-fitting, threadly attaching, fastening with a fastener,combination of the foregoing, or another suitable technique. In otherembodiments, each of the superhard raceway elements 922 may be partiallydisposed in a common slot for all of the superhard raceway elements 922formed in the support ring 918. Superhard raceway elements 922 may beconfigured to at least partially define a raceway curved to liesubstantially on an imaginary spherical surface.

In addition, superhard raceway elements 910 may be positioned betweeninner shoulder 908A and upper shoulder 908D on an inner surface ofsupport ring 908. Each of the superhard raceway elements 910 may bepartially disposed in a corresponding recess formed in the inner surfaceof support ring 908 and secured partially therein via brazing,press-fitting, threadly attaching, fastening with a fastener,combination of the foregoing, or another suitable technique. In otherembodiments, each of the superhard raceway elements 910 may be partiallydisposed in a common slot for all of the superhard raceway elements 910formed in the support ring 908. Superhard raceway elements 910 may beconfigured to form at least a portion of a raceway curved to liesubstantially on an imaginary spherical surface.

As shown in FIG. 5, in an embodiment, roller assembly 906 may comprise aplurality of generally spherical rolling elements 928 configured to rollor run on the raceway between the inner race 902 and outer race 904.Such a configuration provides the ability to support both thrust andradial loads. In an embodiment, the geometry of angular contact ballbearing apparatus 900 may be selected to influence operation of angularcontact ball bearing apparatus 900. For example, the capacity of angularcontact ball bearing apparatus 900 to support thrust loads may increaseby increasing a contact angle α. The contact angle α is the anglebetween a line joining points of contact of the rolling element 928 andthe portions of the raceway, along which the load is transmitted fromone raceway to another, and a line generally perpendicular to the axis914. In addition, due to displacement between the portions of theraceway formed on the support rings 908, 918 and/or the curvature of theraceway, angular contact ball bearing apparatus 900 may allow for somedegree of shaft misalignment or deflection during operation. Such aconfiguration may allow angular contact ball bearing apparatus 900 totolerate burst of wind and/or other high impact loads that may bepresent during operation of wind turbine systems or other systems.

Superhard raceway element 910 and/or 922 may include any of thematerials discussed above in relation to superhard bearing elements 110(e.g., superhard materials). In addition, rolling elements 928 mayinclude any of the materials discussed in relation to rolling elements128 (e.g., superelastic materials). Like the other roller bearingapparatuses, the material design of the superhard raceway elements 910,922, and/or rolling elements 928 may be configured to influence theoperational life and/or performance of angular contact ball bearingapparatus 900. For example superhard raceway elements 910, 922 may beconfigured to exhibit a modulus of elasticity that exceeds a modulus ofelasticity of one or more of the rolling elements 928 such thatresistance of the angular contact ball bearing apparatus 900 to shock,vibration loading, and/or common failure modes such as welding, galling,and/or scuffing may be enhanced.

The roller bearing apparatuses described herein may be employed in avariety of mechanical applications. For example, pumps, turbines, gearboxes or transmissions may benefit from a roller bearing apparatusdisclosed herein. FIG. 6 is a partial isometric cutaway view of a windturbine system 500 according to an embodiment. The system 500 mayinclude a housing 544 and a main gear shaft 546 operably connected to awind turbine, i.e., blades attached to a hub, (not shown). A pair oftapered roller bearing apparatuses 550 may be operably connected to themain shaft 546. In an embodiment, each of the tapered roller bearingapparatus 550 may be configured similar to tapered roller bearingapparatus 400. For example, each tapered roller bearing apparatus 550may include an inner race 502 (i.e., rotor), an outer race 504 (i.e.,stator), and a roller assembly 506. The shaft 546 may extend through theinner races 502 and may be secured to each inner race 502 by pressfitting or otherwise attaching the gear shaft 546 to the inner race 502,threadly coupling the shaft 546 to the inner race 502, or anothersuitable technique.

In an embodiment, the roller assembly 506 may be interposed between theinner race 502 and the outer race 504. The roller assembly 506 mayinclude a cage 526 having a plurality of cage pockets (not shown) forretaining a plurality of rolling elements 528. The cage 526, includingthe rolling elements 528, may form at least a portion of a cone (e.g.,frustoconical ring). In an embodiment, the rolling elements 528 mayexhibit a generally cylindrical geometric shape and may be rotatablymounted within the cage pockets. In other embodiments, at least one ofthe rolling elements 528 may exhibit a generally spherical geometricshape, a generally conical shape, or any other suitable geometric shape.The rolling elements 528 may include any of the materials discussedabove for the rolling elements 128. For example, one or more of therolling elements 528 may include one or more superelastic materials suchthat the portion of the rolling elements 528 in contact with the racewayexhibit non-linear elastic deformation and generally conform to theraceway during use. Such a configuration may help reduce stressesexperienced by and/or failure of (e.g., flaking, strain, pitting, orcombinations thereof) the rolling elements, the superhard racewayelements, and/or the support rings.

In an embodiment, the inner race 502 may include a support ring 508 anda plurality of superhard raceway elements 510 mounted or otherwiseattached to the support ring 508. Each of the superhard raceway elements510 may include a convexly-curved raceway surface 518. As illustrated,the superhard raceway elements 510 may be configured and located toprovide a raceway for the rolling elements 528 to roll over/run on. Inan embodiment, the superhard raceway elements 510 may be located on thesupport ring 508 such that gaps 532 or other offsets are formed betweenadjacent ones of the superhard raceway elements 510. A width of one ormore of the gaps 532 or an average width of the gaps 532 may be about0.00020 inches (0.00508 mm) to about 0.100 inches (2.54 mm), and moreparticularly about 0.00020 inches (0.00508 mm) to about 0.020 inches(0.508 mm). In other embodiments, one or more of the gaps 132 mayexhibit larger or smaller widths. Optionally, one or more of the gaps532 may exhibit a relatively small width configured to help limitlubricating fluid from being able to leak between adjacent superhardraceway elements 510. For example, the superhard raceway elements 510may be located on the support ring 508 such that the superhard racewayelements 510 are immediately adjacent to one another to form a closelyspaced plurality of the superhard raceway elements 510 at leastpartially defining the raceway. In other embodiments, the superhardraceway elements 510 may be located on the support ring 508 such thatthe superhard raceway elements 510 form a substantially contiguoussuperhard raceway. In other embodiments, one or more of the gaps 532 mayexhibit a relatively large width configured to improve heat transfer.Thus, by varying the configuration and size of the gaps 532, the gaps532 may be optionally configured to impart a desired amount of heattransfer and/or hydrodynamic film formation on the raceway duringoperation. While the inner race 502 is shown having one row of thesuperhard raceway elements 510, the inner race 502 may include two rows,three rows, or any suitable number of rows of the superhard racewayelements 510.

In an embodiment, the outer race 504 may extend about and receive theinner race 502 and the roller assembly 506. The outer race 504 mayinclude a support ring 520 and a plurality of superhard raceway elements522 mounted or otherwise attached to the support ring 520. Each of thesuperhard raceway elements 522 may include a concavely-curved racewaysurface 524. Like the superhard raceway elements 510, the superhardraceway elements 522 may be configured to at least partially define theraceway for the rolling elements 528 to roll over or run on. While theouter race 504 is shown including one row of the superhard racewayelements 522, the outer race 504 may include two rows, three rows, orany number of suitable rows of the superhard raceway elements 522.

The terms “rotor” and “stator” refer to rotating and stationarycomponents of the tapered roller bearing apparatuses 550. Thus, if theouter race 504 is configured to remain stationary, the outer race 504may be referred to as the stator and the inner race 502 may be referredto as the rotor (or vice versa). Moreover, while the thrust rollerbearing apparatuses 550 are illustrated as being similarly configured,the roller bearing apparatuses 550 may have different configurations.For example, one of the thrust roller bearing apparatuses 550 may beconfigured similar to the thrust roller bearing apparatus 400 and theother roller bearing apparatus 550 may be configured as an angularcontact bearing.

In an embodiment, wind may turn the blades on the wind turbine (notshown), which in turn may rotate the main shaft 546 about a rotationaxis 514. The main shaft 546 may rotate the inner race 502 about therotation axis 514, which, in turn, may cause the rolling elements 528 toroll or run on the superhard raceway elements 510 and the superhardraceway elements 522. Similar to thrust bearing apparatus 400, the coneand cup design of the inner race 502 and the outer race 504 may help thetapered roller bearing apparatuses 550 tolerate at least some amount ofaxial and/or radial misalignment and/or deflection between the innerrace 502 and the outer race 504. As shown, the main shaft 546 may gothrough a gear transmission box 511. For example, the main shaft 546 maybe connected to a first gear 511A that turns a second gear 511B or viceversa. The first gear 511A may be larger than the second gear 511B. Thesecond smaller gear 511B may be connected to a shaft 547 that turns agenerator (not shown) to produce electricity.

As wind speed increases and energy builds within the system 500, thehigh thermal conductivity of the superhard raceway elements 510, 522 mayhelp remove heat from the contact surface between the rolling elements528 and the superhard raceway elements. Such a configuration may helpreduce the likelihood of temperature induced strength reductions and/orfailure in the radial bearing apparatuses 550. Further, when the racewaysurfaces 518, 524 are subjected to vibration under load with minimalrolling movement, the high modulus contrast between the rolling elements528 and the raceway may help provide resistance to shock and vibrationloading. Such a configuration may help reduce the likelihood offretting, micro pitting, and/or other types of wear in the radialbearing apparatuses 550. This is particularly advantageous given thefrequent starts and stops of the system 500. Moreover, in an embodiment,differences between the elasticity of superhard materials formingraceway and the selected materials of the rolling elements 528 may helpreduce the likelihood of adhesion.

FIG. 7 is an isometric cutaway view of a thrust bearing roller bearingapparatus 600 according to an embodiment. The thrust roller bearingapparatus 600 may include a stator 602, a roller assembly 606, and arotor 604. The roller assembly 606 may be interposed between the stator602 and the rotor 604. The roller assembly 606 may optionally include acage 626 having a plurality of cage pockets 630 formed in the cage 626for retaining a plurality of rolling elements 628. Each of the cagepockets 630 may exhibit a substantially rectangular geometric shape andmay be distributed circumferentially about a thrust axis 614 along whicha thrust force may be generally directed during use. In otherembodiments, the cage pockets 630 may exhibit a generally oval, agenerally circular, or any other suitable geometric shape. The cagepockets 630 may be arranged in a single row about the thrust axis 614.In other embodiments, the cage pockets 630 may be arranged in two rows,three rows, or any suitable number of rows. The cage 626 may be madefrom a variety of different materials including carbon steel, stainlesssteel, cemented tungsten carbide, and the like.

The rolling elements 628 may be rotatably mounted within the cagepockets 630 and may be positioned substantially perpendicular to thethrust axis 614. As illustrated, the rolling elements 628 may begenerally cylindrical. In other embodiments, the rolling elements 628may be generally spherical or other suitable geometric shapes. One ormore of the rolling elements 628 may be formed from any of the materialsdiscussed above for the rolling elements 128. For example, the rollingelements 628 may include one or more superelastic materials such thatthe rolling elements 628 exhibit non-linear elastic deformation andgenerally conform to the raceway during use.

The stator 602 may include a support ring 608 defining an opening 612through which a shaft may extend. The support ring 608 may be made froma variety of different materials such as carbon steel, stainless steel,tungsten carbide, combinations thereof, or another suitable material.The stator 602 may further include a plurality of superhard racewayelements 610 and a plurality of interconnected recesses 616 formed inthe support ring 608. Each of the superhard raceway elements 610 may bepartially disposed in a corresponding one of the recesses 616 viabrazing, press-fitting, or another suitable technique. In anotherembodiment, each of the superhard raceway elements 610 may be partiallydisposed in a common slot for all of the superhard raceway elements 610formed in the support ring 608.

The superhard raceway elements 610 are illustrated being distributedcircumferentially about the thrust axis 614. In the illustratedembodiment, each of the superhard raceway elements 610 may comprise asuperhard table 634 including a raceway surface 618, with the superhardtable 634 bonded to a substrate 636. However, in other embodiments, allor some of the superhard raceway elements 610 may be different or evensubstrateless. In an embodiment, the raceway surfaces 618 may besubstantially coplanar to one another. The superhard raceway elements610 may each be made from any of the materials discussed above for thesuperhard raceway elements 110. For example, the superhard racewayelements 610 may be made from polycrystalline diamond or any othersuitable superhard materials. As shown, the superhard raceway elements610 may exhibit a geometric shape that is generally formed by theintersection of two cylinders. In other embodiments, the superhardraceway elements 610 may exhibit a generally oval geometric shape, agenerally rectangular geometric shape, a wedge-like shape, or any othersuitable geometric shape.

The superhard raceway elements 610 may be circumferentially distributedabout the thrust axis 614 such that gaps between adjacent ones of thesuperhard raceway elements 610 are occupied by a portion of the supportring 608. Such a configuration may increase the surface area of thesupport ring 608 in contact with the superhard raceway elements 610 tohelp affix the superhard raceway elements 610 to the support ring 608.In other embodiments, the superhard raceway elements 610 may becircumferentially distributed about the thrust axis 614 such that thesuperhard raceway elements 610 generally abut one another.

In an embodiment, the superhard raceway elements 610 may be configuredand located on the support ring 608 to at least partially define araceway for the rolling elements 628 to roll over or run on. By formingthe raceway with the superhard raceway elements 610 and forming therolling elements 628 with one or more materials having a lowerelasticity (e.g., superelastic materials), deformation of the supportring 608 and/or risk of fatigue and eventual failure may be reduced. Inaddition, the configuration of the superhard raceway elements 610 andthe rolling elements 628 may enhance the general load capacity of thethrust roller bearing apparatus 600 and/or reduce friction.

The rotor 604 may be configured similar to the stator 602. For example,the rotor 604 may include a support ring 620 and a plurality ofsuperhard raceway elements 622 mounted or otherwise attached to thesupport ring 620, with each of the superhard raceway elements 622 havinga raceway surface 624. Like the superhard raceway elements 610, thesuperhard raceway elements 622 may be configured and positioned on thesupport ring 620 to at least partially define the raceway for therolling elements 628 to run over or roll on during use of the thrustroller bearing apparatus 600. In an embodiment, the support ring 608and/or the support ring 620 may include a flange 642 configured to helpmaintain the rolling elements 628 between the stator 602 and the rotor604. In other embodiments, the flange 642 may be omitted.

It is noted that in other embodiments, the disclosed thrust rollerbearing apparatuses may be used in a number of applications, such assubterranean drilling systems, directional drilling systems, pumps,transmissions, gear boxes, and many other applications.

FIG. 8 is an exploded isometric view of a tapered thrust roller bearingapparatus 700 according to another embodiment. The tapered thrust rollerbearing apparatus 700 may include a stator 702, a roller assembly 706,and a rotor 704. The roller assembly 706 may be interposed between thestator 702 and the rotor 704. The roller assembly 706 may optionallyinclude a cage 726 having a plurality of cage pockets 730 formed in thecage 726 configured to retain a plurality of rolling elements 728. Eachof the cage pockets 730 may have a substantially trapezoidal shape andmay be distributed circumferentially about a thrust axis 714. The cage726 may be made from one or more selected materials, such as carbonsteel, stainless steel, tungsten, carbide material, combinationsthereof, or any other suitable material. The rolling elements 728 may berotatably mounted within the cage pockets 730. The rolling elements 728may be generally conical having generally planar end portions (e.g.,frustoconical). In other embodiments, one or more of the rollingelements 728 may have at least one generally curved end portion,generally concave end portion, generally convex end portion, generallypointed end portion, combinations thereof, or other suitable end portionconfigurations. One or more of the rolling elements 728 may be formedfrom any of the materials discussed above for the rolling elements 128.

The stator 702 may include a plurality of circumferentially adjacentsuperhard raceway elements 710 distributed about a thrust-axis 714 andconfigured and located to at least partially define a raceway for therolling elements 728 to roll on or run over. The superhard racewayelements 710 may each include a raceway surface 718 configured tosubstantially lie on an imaginary conical surface. The superhard racewayelements 710 may exhibit a geometric shape that is generally formed bythe intersection of two cylinders (e.g., lune, lens, orcrescent-shaped). In other embodiments, at least one of the superhardraceway elements 710 may be generally trapezoidal, generally elliptical,combinations thereof, or any other suitable geometric shape. In anembodiment, the superhard raceway elements 710 may be mounted orotherwise attached to at least a lower surface 708D of the support ring708. As shown, the support ring 708 may include an upper surface 708C,the lower surface 708D, an inner surface 708A, and an outer surface708B. In an embodiment, the inner surface 708A and the outer surface708B may extend between the upper surface 708C and the lower surface708D. The inner surface 708A may be generally concentric and/orcongruent relative to the outer surface 708B. In other embodiments, atleast a portion of the inner surface 708A may be generally incongruentand/or not centered relative to at least a portion of the outer surface708B. As illustrated, the lower surface 708D may form an angle relativeto the upper surface 708C and may form at least a portion of a generallyconical surface. For example, the lower surface 708D may extend andtaper between the inner surface 708A and the outer surface 708B.

The rotor 704 may include a support ring 720 and a plurality ofsuperhard raceway elements 722, with each of the superhard racewayelements 722 having a raceway surface 724 configured to lie on animaginary conical surface. As shown, the superhard raceway elements 722may have a geometric shape that is generally formed by the intersectionof two cylinders. In other embodiments, the superhard raceway elements722 may have a geometric shape that is generally oval, generallywedge-like, or any other suitable geometric shape. Like the superhardraceway elements 710, the superhard raceway elements 722 may beconfigured and positioned on the support ring 720 to at least partiallydefine a raceway for the rolling elements 728 to run over or roll onduring use. In an embodiment, the superhard raceway elements 722 may bemounted or otherwise attached to at least an upper surface 720C of thesupport ring 720. As shown, the support ring 720 may include the uppersurface 720C, a lower surface 720D, an inner surface 720A, and an outersurface 720B. In an embodiment, the inner surface 720A and the outersurface 720B may extend between the upper surface 720C and the lowersurface 720D. The inner surface 720A may be generally concentric and/orcongruent relative to the outer surface 720B. In other embodiments, atleast a portion of the inner surface 720A may be generally incongruentand/or not centered relative to at least a portion of the outer surface720B. As illustrated, the upper surface 720C of the support ring 720 mayform an angle relative to the lower surface 720D and may form at least aportion of a generally conical surface or a partial conical surface. Forexample, the upper surface 720C may generally extend and taper betweenthe inner surface 720A and the outer surface 720B. In an embodiment, thesupport ring 720 and/or the support ring 708 may include a flangefeature configured to help maintain the rolling elements 728 between thestator 702 and the rotor 704. In other embodiments, the flangefeature(s) may be omitted. It is noted that in other embodiments, therotor or stator may be configured as any of the previously describedembodiments of thrust roller bearing assemblies.

Any of the embodiments for roller bearing apparatuses discussed abovemay be used in a subterranean drilling system. FIG. 9 is a schematicisometric cutaway view of a subterranean drilling system 800 accordingto an embodiment. The subterranean drilling system 800 may include ahousing 860 enclosing a downhole drilling motor 862 (i.e., a motor,turbine, or any other device capable of rotating an output shaft) thatmay be operably connected to an output shaft 856. A thrust rollerbearing apparatus 864 may be operably coupled to the downhole drillingmotor 862. The thrust roller bearing apparatus 864 may be configured asany of the previously described thrust roller bearing apparatusembodiments. A rotary drill bit 868 may be configured to engage asubterranean formation and drill a borehole and may be connected to theoutput shaft 856. The rotary drill bit 868 is shown comprising a bitbody 890 that includes radially and longitudinally extending blades 892with a plurality of polycrystalline diamond cutting elements 894 securedto the blades 892. However, other embodiments may utilize differenttypes of rotary drill bits, such as core bits and/or roller-cone bits.As the borehole is drilled, pipe sections may be connected to thesubterranean drilling system 800 to form a drill string capable ofprogressively drilling the borehole to a greater depth within the earth.

The thrust roller bearing apparatus 864 may include a stator 872 thatdoes not rotate and a rotor 874 that may be attached to the output shaft856 and rotates with the output shaft 856. The thrust roller bearingapparatus 864 may further include a roller assembly (not shown)interposed between the stator 872 and the rotor 874. The roller assemblymay include a cage having a plurality of cage pockets (not shown) forretaining a plurality of rolling elements (not shown). As discussedabove, the thrust roller bearing apparatus 864 may be configured as anyof the embodiments disclosed herein. For example, the stator 872 mayinclude a plurality of circumferentially-distributed superhard racewayelements configured to at least partially define a raceway for therolling elements to roll over or run on. In addition, the rotor 874 mayinclude a plurality of circumferentially-distributed superhard racewayelements and configured to provide a raceway surface for the rollingelements to roll or run on. The rolling elements may, for example,include one or more superelastic materials such that the rollingelements exhibit non-linear elastic deformation and generally conform tothe raceway during use.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments are contemplated. The various aspects andembodiments disclosed herein are for purposes of illustration and arenot intended to be limiting. Additionally, the words “including,”“having,” and variants thereof (e.g., “includes” and “has”) as usedherein, including the claims, shall be open ended and have the samemeaning as the word “comprising” and variants thereof (e.g., “comprise”and “comprises”).

What is claimed is:
 1. A method of operating a bearing assembly thatincludes a first raceway and a second raceway, the method comprising:rotating the first raceway relative to the second raceway, the firstraceway including a plurality of first superhard raceway elements havinga first modulus of elasticity; rolling one or more rolling elementsbetween the first and second raceways and on the plurality of firstsuperhard raceway elements, the one or more rolling elements having asecond modulus of elasticity that is three (3) times greater to aboutfifty (50) times greater than the first modulus of elasticity.
 2. Themethod of claim 1, wherein rotating the first raceway relative to thesecond raceway causes the rolling of the one or more rolling elements.3. The method of claim 1, wherein rolling one or more rolling elementsbetween the first and second raceways and on the plurality of firstsuperhard raceway elements includes rolling the one or more rollingelements in contact with at least some of the plurality of firstsuperhard raceway elements.
 4. The method of claim 1, wherein the secondraceway includes a plurality of second superhard raceway elements, andwherein rolling one or more rolling elements between the first andsecond raceways and on the plurality of first superhard raceway elementsincludes rolling the one or more rolling elements in contact with one ormore of the plurality of first superhard raceway elements and theplurality of second superhard raceway elements.
 5. The method of claim1, wherein the one or more rolling elements include a superelasticmaterial.
 6. The method of claim 1, wherein the second raceway includesa plurality of second superhard raceway elements generally opposing theplurality of first superhard raceway elements.
 7. The method of claim 1,wherein each of the first and second raceways is substantially planar,substantially cylindrical, or substantially conical.
 8. The method ofclaim 1, wherein one or more of the plurality of first superhard racewayelements include a concavely-curved raceway surface or a convexly-curvedraceway surface.
 9. The method of claim 1, wherein at least some of theplurality of first superhard raceway elements include polycrystallinediamond.
 10. The method of claim 1, wherein the first raceway, thesecond raceway, and the one or more rolling elements form a radialbearing assembly, a thrust-bearing assembly, or a tapered bearingassembly.
 11. The method of claim 1, wherein the first plurality ofsuperhard raceway elements includes gaps between adjacent ones of theplurality of first superhard raceway elements, and wherein one or moreof the first plurality of superhard raceway elements include at leastone side surface forming a respective oblique angle relative to theaxis, and wherein the respective oblique angle is selected to at leastpartially inhibit the gaps from impeding the one or more rollingelements during operation.
 12. The method of claim 11, wherein therespective oblique angle is greater than about forty (40) degrees. 13.The method of claim 11, wherein the respective oblique angle is greaterthan about forty (40) degrees.
 14. A method of operating a bearingassembly, the method comprising: rotating a first raceway relative to asecond raceway, the first raceway including a plurality of firstsuperhard raceway elements having a first modulus of elasticity, and thesecond raceway including a plurality of second superhard racewayelements; rolling one or more rolling elements between the first andsecond raceways and on the plurality of first superhard raceway elementsand the plurality of second superhard raceway elements, the rollingelements including one or more superelastic materials.
 15. The method ofclaim 14, wherein the one or more rolling elements are generallyelongated rolling elements.
 16. The method of claim 15, wherein thegenerally elongated rolling elements include a core body at leastpartially surrounded by the one or more superelastic materials.
 17. Themethod of claim 15, wherein the generally elongated rolling elementsincludes a hollow cylindrical body.
 18. The method of claim 15, furthercomprising a cage that retains the generally elongated rolling elementsbetween the first raceway and the second raceway.
 19. A method ofoperating a bearing assembly, the method comprising: rotating a firstraceway relative to a second raceway, the first raceway including aplurality of first superhard raceway elements having a first modulus ofelasticity, and the second raceway including a plurality of secondsuperhard raceway elements; rolling one or more rolling elements betweenthe first and second raceways and on the plurality of first superhardraceway elements and the plurality of second superhard raceway elements,one or more of the plurality of first superhard raceway elements or theplurality of second superhard raceway elements having a thermalconductivity of at least 300 W/m-K.
 20. The method of claim 19, whereinthe thermal conductivity is about 700 W/m-K to about 1600 W/m-K.